This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Trace metal ions play a critical role in biology. One critical aspect of understanding the inorganic physiology of trace metals is detection of the distribution of the elements in tissues. We have identified three systems that would best exploit XRF imaging to give insight into metal homeostasis. Drosophila has the ability to sequester high levels of copper, resulting in a beneficial effect on the future generations. The offspring of parents that have been exposed to high copper levels are able to overcome developmental delays associated with copper scarcity. XRF imaging would be used to locate where this large amount of sequestered copper is stored and if this copper can be passed on to offspring. The second project deals with the copper hierarchy in Zebrafish. Zebrafish embryos with increasing levels of copper deficiency have been designed using genetic mutation and copper chelators. As copper levels decrease, non-essential copper dependent processes, such as pigmentation, are lost. Then notochord development is affected and finally neurological deformation. A copper hierarchy has been identified where copper is target to more essential systems first and then to non-essential systems. It is unknown whether this hierarchy is enforced on a systemic level or a cellular level, is copper targeted to the cells responsible for neurological development over those responsible for pigmentation, or is copper delivery equal in all cells but the threshold cellular copper levels need to express the proteins responsible for pigmentation higher that those needed for expression of more essential proteins. The final system involves loss of zinc secretion in prostate cancer cells. Healthy prostate glands are extremely active zinc secreting glands. It is known that prostate cancer cells show a large reduction in the concentration of zinc. XRF imaging will be used to compare different stages of prostate cancer to determine when the zinc incorporation is reduced.